This project examines how the format of engagement between preschoolers with ASD and their parents influences later language and social communication development. Parent-child engagement during toy play is an important locus of development. Parents provide essential scaffolds for their children in sustaining reciprocal engagement during play. This scaffolding includes linguistic input that aligns with the child’s focus of attention. Children with ASD may benefit from especially responsive parental interactions that maintain an optimal level of engagement to promote language and communication. Currently, we are planning a study in which typically developing infants aged 6 to 25 months will be compared to a group of children with ASD to better understand the types of engagement and parental language that leads to increased child language and social growth.